1. Field of the Invention
The present invention relates to a system requiring recording and/or reproduction in real time, and more particularly, to a recording medium for storing real time recording/reproduction information, a method and apparatus for recording and reproducing a real time file based on the real time recording/reproduction information, and a file operating method using the real time recording/reproduction information.
2. Description of the Related Art
In a computer or audio and/or video (A/V) apparatus constituted of a file system for an A/V file required to be recorded/reproduced in real time, control information representing that the A/V file is a real time recording/reproduction file is not recorded in file control information. Thus, it is impossible to reproduce in real time a file comprised of data blocks physically scattered on a recording medium even if they are logically successive.
Here, a conventional file system, as shown in FIG. 1, is comprised of file control information having the length of a file, information on the position of file data, information on the possibility or impossibility of reading/writing a file, etc., and file data stored in positions designated by the file control information. When a file on a disc is read, file control information is first read, and file data in the positions designated by the read file control information is then read and reproduced. Such a method of allocating a block of a fixed size used in the conventional file system cannot guarantee real time reproduction of a file.
That is, recording/reproduction of the conventional file system is described by taking as an example the case in which two files occupy blocks on a disc as shown in FIG. 2. Here, a file A, requiring real time reproduction, occupies blocks 0, 3, 5 and 6 of the disc, and a file B, a general file, occupies blocks 1, 2, 4 and 7 of the disc.
The process for reproducing the file A is as follows.
In the first step, block 0 is read. In the second step, block 3 is searched for. In the third step, block 3 is read and played back. In the fourth step, the block 5 is searched for. In the fifth step, blocks 5 and 6 are read and played back. In the conventional file system, since information associated with real time recording/reproduction is not recorded even when recording a file requiring real time recording/reproduction, a data arrangement for real time recording/reproduction is not considered. Thus, real time reproduction may not be achieved.
That is, the file A (for example, a video file) of FIG. 2 requires real time reproduction, but the conventional file system arranges data files without consideration of the requirement of real time reproduction, thus causing a screen to be interrupted during playback. In order to record/reproduce files in real time, the sum of a seek time and a read time must be smaller than a playback time, as shown in the following expression:seek time+read time<playback time  (1)
In order to prevent a screen from being interrupted, a next block must be searched for during reading and reproducing a current block before the next block is read. However, in an apparatus for driving a disc such as a compact disc (CD) and a digital versatile disc (DVD), the seek time is significantly longer than the read time. Therefore, real time reproduction is impossible if the next block is not physically adjacent to the current block.